You are in: eMedicine Specialties > Trauma > Thoracic Trauma Tension PneumothoraxArticle Last Updated: Jun 21, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: H Scott Bjerke, MD, FACS, Clinical Associate Professor, Department of Surgery, Indiana University School of Medicine, Medical Director of Trauma Services, Methodist Hospital, Clarian Health Partners, Inc H Scott Bjerke is a member of the following medical societies: American Association for the History of Medicine, American Association for the Surgery of Trauma, American College of Surgeons, Association for Academic Surgery, Eastern Association for the Surgery of Trauma, Midwest Surgical Association, National Association of EMS Physicians, Pan-Pacific Surgical Association, Royal Society of Medicine, Southwestern Surgical Congress, and Wilderness Medical Society Editors: Marc D Basson, MD, PhD, Chief of Surgery, John D Dingell VA Medical Center; Professor, Department of Surgery, Wayne State University School of Medicine; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Robert L Sheridan, MD, Assistant Chief of Staff, Chief of Burn Surgery, Shriners Burns Hospital; Associate Professor of Surgery, Department of Surgery, Division of Trauma and Burns, Massachusetts General Hospital and Harvard Medical School; Paolo Zamboni, MD, Professor of Surgery, Chief of Day Surgery Unit, Chair of Vascular Diseases Center, University of Ferrara, Italy; John Geibel, MD, DSc, MA, Professor, Department of Surgery, Section of Gastrointestinal Medicine and Department of Cellular and Molecular Physiology, Yale University School of Medicine; Director of Surgical Research, Department of Surgery, Yale-New Haven Hospital Author and Editor Disclosure Synonyms and related keywords: collapsed lung INTRODUCTIONSection 2 of 12
  Tension pneumothorax is the accumulation of air under pressure in the pleural space. This condition develops when injured tissue forms a 1-way valve, allowing air to enter the pleural space and preventing the air from escaping naturally. Arising from numerous causes, this condition rapidly progresses to respiratory insufficiency, cardiovascular collapse, and, ultimately, death if unrecognized and untreated. Favorable patient outcomes require urgent diagnosis and immediate management. Tension pneumothorax is a clinical diagnosis that now is more readily recognized because of improvements in emergency medical services (EMS) and the widespread use of chest x-rays. History of the ProcedurePhysicians defined pneumothorax during the reign of Alexander the Great. Many of the early references to pneumothorax actually may have been tension pneumothorax, which can be significantly more dramatic in its clinical presentation. Needle decompression of the chest for presumed tension pneumothorax has been in practice for nearly 20 years, but little data exist in the medical literature showing the efficacy of the procedure or reviewing the field-use and incidence of the procedure. Tension pneumothorax remains a life-threatening condition diagnosed under difficult conditions, with a simple emergency procedure as treatment (ie, needle decompression). While commonly used, proving the efficacy of the emergency treatment or its incidence in actual population studies is nearly impossible. ProblemAir trapping in the pleural cavity and causing shifts of the intrathoracic structure is a life-threatening emergency. Promptly recognizing this condition saves lives, both outside the hospital and in a modern intensive care unit (ICU). Because this condition occurs infrequently and has potentially devastating effects, a high index of suspicion and knowledge of basic emergency thoracic decompression are important for all health care personnel. While some authors are now questioning the pathophysiology of the disease, no animal models or randomized prospective trials have provided any evidence that our understanding of the cause, effects, and treatment of the disease should be changed. FrequencyThe actual incidence outside of a hospital setting is impossible to determine. The 1999 revision of the Department of Transportation (DOT) Emergency Medical Treatment (EMT) Paramedic curriculum recommends emergent needle decompression of the chest in patients exhibiting nonspecific signs and symptoms. Approximately 10-30% of patients transported to level-1 trauma centers in the US receive prehospital decompressive needle thoracostomies; however, not all of these patients actually have a true tension pneumothorax. While this occurrence rate may seem high, disregarding the diagnosis probably results in unnecessary deaths. The overall incidence of tension pneumothorax in the ICU is unknown. The medical literature provides only glimpses of the frequency. From the 2000 incidents reported to the Australian Incident Monitoring Study (AIMS), 17 involved actual or suspected pneumothoraces, and 4 of those were diagnosed as tension pneumothorax. A more recent review of military deaths from thoracic trauma suggests that up to 5% of combat casualties with thoracic trauma have tension pneumothorax at the time of death. EtiologyThe most common etiologies are either iatrogenic or related to trauma. They include the following:
PathophysiologyTension pneumothorax occurs anytime a disruption involves the visceral pleura, parietal pleura, or the tracheobronchial tree. The disruption occurs when a 1-way valve forms, allowing air inflow into the pleural space and prohibiting air outflow. The volume of this nonabsorbable intrapleural air increases with each inspiration because of the 1-way valve effect. As a result, pressure rises within the affected hemithorax. As the pressure increases, the ipsilateral lung collapses and causes hypoxia. Further pressure build-up causes the mediastinum to shift toward the contralateral side and impinge on both the contralateral lung and the vasculature entering the right atrium of the heart. This condition leads to worsening hypoxia and compromised venous return. The inferior vena cava is thought to be the first to kink and restrict blood flow back to the heart. It is most evident in trauma patients who may be hypovolemic with reduced venous blood return to the heart. Researchers still are debating the exact mechanism of cardiovascular collapse, but, generally, they believe the condition develops from a combination of mechanical and hypoxic effects. The mechanical effects manifest as kinking or compression of the superior and inferior vena cava because the mediastinum deviates and the intrathoracic pressure increases. Hypoxia leads to increased pulmonary vascular resistance via vasoconstriction. In either event, decreasing cardiac output and worsening metabolic acidosis secondary to decreased oxygen delivery to the periphery occur, thus inducing anaerobic metabolism. If the underlying problem remains untreated, the hypoxemia, metabolic acidosis, and decreased cardiac output lead to cardiac arrest and death. ClinicalClinical interpretation of the presenting signs and symptoms is crucial for diagnosing and treating the condition.
These findings may be affected by the volume status of the patient. In hypovolemic trauma patients with ongoing hemorrhage, the physical findings may lag behind the presentation of shock and cardiopulmonary collapse. In nonventilated patients, diagnosis often requires a high level of suspicion and the presence of decreased or absent breath sounds on the affected side. In ventilated patients, the physician may begin to suspect tension pneumothorax when increased pleural pressures necessitate an increase in peak airway pressure in order to deliver the same tidal volume. Decreased expiratory volumes secondary to air leakage into the pleural space and increased end-expiratory pressure, even after discontinuation of PEEP, are 2 other signs of tension pneumothorax in these patients. Occasionally, the development of tension pneumothorax may be delayed for hours to days after the initial insult, and the diagnosis may become evident only if the patient is receiving positive-pressure ventilation. Tension pneumothorax has been reported during surgery with both single and double lumen tubes. Increased pulmonary artery pressures and decreased cardiac output or cardiac index are evidence of tension pneumothorax in patients with Swan-Ganz catheters. INDICATIONSSection 3 of 12
If signs and symptoms attributable to a clinical diagnosis of tension pneumothorax are present, aggressively manage with needle decompression of the chest. RELEVANT ANATOMYSection 4 of 12
Under emergency circumstances, place decompression catheters in the second rib interspace in the midclavicular line. This punctures through the skin and, possibly, through the pectoralis major muscle, external intercostals, internal intercostals, and parietal pleura. Placement in the middle third of the clavicle minimizes the risk of injury to the internal mammary during the emergency procedure. Place the catheter just above the cephalad border of the rib because the intercostal vessels are largest on the lower edge of the rib. CONTRAINDICATIONSSection 5 of 12
If tension pneumothorax is suspected, make sure no contraindications exist for the placement of an emergency decompression catheter into the thorax. Contraindications can include previous thoracotomy, previous pneumonectomy, and the presence of a coagulation disorder. These are relative contraindications, however, because tension pneumothorax is a life-threatening condition, and failure to treat expectantly can result in patient death. WORKUPSection 6 of 12
Lab Studies
Imaging Studies
TREATMENTSection 7 of 12
Medical therapyNo acceptable noninvasive therapy exists for this emergent life-threatening condition. Surgical therapyTension pneumothorax is a life-threatening condition that demands urgent management. If this diagnosis is suspected, do not delay treatment in the interest of confirming the diagnosis.
Emergent needle decompression The basic principle is to introduce a catheter into the pleural space, thus producing a pathway for the air to escape and relieving the built-up pressure. Although this procedure is not the definitive treatment for tension pneumothorax, emergent needle decompression does arrest its progression and serves to restore cardiopulmonary function slightly. Needle length in persons with large pectoral muscles may be an issue, and long needles or angiocatheters may be necessary.
Tube thoracostomy
Follow-upWhile the patient is on positive-pressure ventilation and normal respiratory function is preserved, routinely follow up decompressed tension pneumothoraces by watching for recurrence of the condition. Chest x-ray is helpful but not required. For excellent patient education resources, visit eMedicine's Lung and Airway Center. Also, see eMedicine's patient education article Collapsed Lung. COMPLICATIONSSection 8 of 12
Misdiagnosis is the most common complication of needle decompression. If a pneumothorax but not a tension pneumothorax is present, needle decompression converts it to an open pneumothorax. If no pneumothorax exists, the patient will develop a pneumothorax after the needle decompression is performed. Additionally, the needle may lacerate a lung, which is rare but can cause significant pulmonary injury or hemothorax. If the needle initially is placed too medially to the sternum, needle decompression may cause a hemothorax by lacerating the inferior set of intercostal vessels and the internal mammary artery. Thoracostomy tube placement can result in damage to the intercostal neurovascular bundle and can cause lung parenchymal injury, especially if using trocars for its placement. OUTCOME AND PROGNOSISSection 9 of 12
Early diagnosis and immediate treatment promote a good prognosis for patients with tension pneumothorax. Overall patient prognosis greatly depends on associated injuries or morbidities. FUTURE AND CONTROVERSIESSection 10 of 12
No controversy surrounds the emergent decompression of symptomatic tension pneumothorax. Improvement in the accuracy of diagnosis may change according to the changes in the 1999 DOT EMT Paramedic curriculum and the future availability of ultrasound technology for use in the field. Studies performed for National Aeronautics and Space Administration (NASA) that are not yet published suggest that ultrasound is useful in diagnosing pneumothorax, making it potentially useful in emergency situations (eg, tension pneumothorax). MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Article Last Updated: Jun 21, 2006 | |||||||
